A server is often mounted on a rack system with a fan system. Conventionally, the server is mounted in the front side of the rack system with necessary components to operate the server and the fan system is mounted in the rear side of the rack system for thermal management. Often, the fan system does not include a rear fan door to allow the fan system to be opened from the rear side of the rack system. Thus, to repair the fan system, other components located front side of the rack system must be taken out first to take the fan system out of the rack system. Therefore, it was difficult to make a fan repair or replacement, because it was time consuming to power off the server, take the server out from the rack system, and finally remove the fan system off the rack system for repair. When the server is shut down, it may take some time to get back to the operation mode, and during that time, the server cannot function.